From the background art, several pipettes and sampling systems for different media, especially for fluid media, are known. These find application not only in many instances of daily life but also in industrial applications for extracting fluids or other media from a container.
Particularly often the known pipette systems find application in the field of medicine. In these pipette systems the liquid medium is most often drawn into the pipette system by means of a hand-operated piston. In this regard, the operator must orient him/herself to the scaling on the pipette receptacle. In other words, the user can freely move the suction piston of the pipette system within the dosing scale.
Thereby, it is often the case that an over- or under-dosing occurs because the operator draws the suction piston above or below the desired scale as a result of reading errors or reading inaccuracies.
This furthermore means that the dosing is not reproducible because variations can arise with each uptake. Particularly in the medical field, an over- or under-dosing can have negative repercussions. An over-dosing can, for example, be damaging to health, whereas an under-dosing can delay the healing process.
A further disadvantage of pipette systems from the background art is that, during intake of the medium, air bubbles often arise within the area of the dosing volume in the pipette system. These air bubbles can result in the drawn-in amount of the medium not corresponding to the amount on the dosing scale. Furthermore, air inclusions particularly in the medical field can be life-threatening for patients.
A dosing device for drawing-in and discharging of a flowable medium is, for example, known from WO 2004/054720. This dosing device comprises an inlet and an outlet which are arranged separately from one another. A dosing and expulsion chamber is therefore provided between the inlet and the outlet. However, the dosing device is a permanent component of the container from which the medium is extracted and cannot be handled separately from that container.
A further dosing device is known from WO 00/18453. In this case, the desired amount can be adjusted by means of a wheel which is located on a container closure. However, this dosing device is also only able to be used in combination with an associated container.